1. Technical Field
Examples of the invention relate to methods and devices associated with the use of height information in navigation systems. Examples of the invention relate in particular to a database for a navigation system, a method of outputting a three-dimensional representation of a terrain and a method of generating a database for a navigation system. Examples of the invention relate in particular to such devices and methods in which height information is stored in the form of triangulated irregular networks (TINs) respectively defined for tiles of a tiling.
2. Related Art
Height information for a terrain may be used in navigation systems. One exemplary field in which such height information may be used is the outputting of three-dimensional maps. Optical output devices may be used for outputting electronic maps. Since electronic maps may be displayed on screens of small and/or portable devices, they have the advantage of being versatile and compact. Three-dimensional (3D) maps, i.e. perspective representations, may be of particular value to the user owing to their high recognition quality. I.e., the recognition of an environmental region, such as a street intersection, may be facilitated when a three-dimensional map is output, as compared to a conventional two-dimensional representation.
Digital elevation model (DEM) data may be stored in the form of TINs. Good run time performance may be attained when rendering the terrain from TINs. DEM data may be organized in accordance with a tiling, with tiles of the tiling covering the area in which DEM data for the terrain is available for rendering. A tile having rectangular or trapezoidal shapes may be split up into plural triangular patches. For each one of the patches, a TIN may be defined. Thus, plural TINs may be defined for respectively each tile of the tiling.